Аннотация:Quantum back action imposes fundamental sensitivity limits to the majority of quantum measurements.The effect results from the unavoidable contamination of the measured parameter with the quantumnoise of a meter. Back action evading measurements take advantage of the quantum correlationsintroduced by the system under study to the meter and allow overcoming the fundamental limitations.The measurements are frequently restricted in their bandwidth due to a finite response time of thesystem components. Here we show that probing a mechanical oscillator with a dichromatic field withfrequencies separated by the oscillator frequency enables independent detection in two outputs andcomplete subtraction of the measurement noise associated with the quantum back action.